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KMMS > Cell signalling > Flashcards

Cell signalling Flashcards

1
Q

40% of all medications interact with what type of receptors?

A

GPCR

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2
Q

The majority of receptors are made up of

A

proteins

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3
Q

What are the two major categories of receptors

A

Transmembrane/cell surface receptors or cytoplasmic/nuclear receptors

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4
Q

Molecules that are very large or hydrophilic use what type of receptor?

A

Transmembrane/cell surface receptor

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5
Q

Small, hydrophobic molecules use what type of receptor?

A

Cytoplasmic or nuclear receptors

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6
Q

__________ binding changes the activites of the intracellular domains of the receptor, which initiates the response

A

Ligand

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7
Q

What are the four types of intracellular receptors?

A

(1) Ligand-gated ion channels
(2) GPCR
(3) Kinase-linked receptors
(4) Nuclear/cytoplasmic receptors

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8
Q

Name some examples of things that can act as singalling molecules/chemical messengers

A

proteins, peptides, sugars, lipid-derived molecules, hormones, cytokines, NT’s, pheromones, gaseous molecules

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9
Q

Signalling molecules that bind to and ACTIVATE receptors are called _______ or ________.

A

Agonists or ligands

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10
Q

Signalling molecules that bind to and INACTIVATE receptors are called ________ or _________.

A

Antagonists or blockers

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11
Q

The majority of intercellular signals are

A

Chemicals (NT’s, hormones)

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12
Q

What are the three types of intercellular signals?

A

(1) Chemicals
(2) Physical interconnections (tight junctions, gap junctions, desmosomes, etc)
(3) Gaseous

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13
Q

Intracellular signalling triggers activation of the receptor, which leads to…

A

A change in cellular behaviour

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14
Q

Different cells can respond differently to the same signal depending on:

A

(1) The sets of receptors the cell has

(2) The intracellular machinery

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15
Q

Why do drugs sometimes have unwanted side effects?

A

Because cells can respond differently to the same ligand

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16
Q

What are the 5 modes of extracellular signalling?

A

(1) Endocrine- long distance
(2) Paracrine
(3) Neuronal
(4) Autocrine
(5) Juxtacrine

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17
Q

What are the main types of signalling molecules used in endocrine signalling?

A

Hormones

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18
Q

Proteins, cytokines, histamine, and platelet-derived growth factor are examples of what type of signaling molecules?

A

Paracrine

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19
Q

How do cells communicate with one another using paracrine signalling?

A

The signals diffuse LOCALLY to neighbouring cells

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20
Q

Noradrenaline is an example of what type of signalling molecule?

A

Neuronal

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21
Q

Cytokine interleukin 1 monocytes are an example of what type of signalling molecule?

A

Autocrine

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22
Q

These cells secrete signalling molecules that bind to their own receptors to generate a change in their own behaviour

A

Autocrine

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23
Q

This type of signalling can be involved in positive or negative feedback

A

Autocrine

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24
Q

This type of signalling is CONTACT DEPENDANT. Immediate neighbours signal to each other via membrane bound molecules

A

Juxtacrine

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25
Q

Antigen presenting cells are an example of cells that use what type of signalling>

A

Juxtracrine

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26
Q

Communicating junctions and gap junctions are associated with what type of signalling?

A

Juxtacrine

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27
Q

What allows waves of electrical excitation to pass quickly through cardiac cells?

A

Gap junctions (juxtacrine signalling)

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28
Q

What type of signalling is involved in coordinating uterine contractions?

A

Juxtacrine

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29
Q

What are the three stages of intracellular communication?

A

(1) Reception
(2) Transduction
(3) Response

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30
Q

What happens in the first stage of intracellular communication- “reception?”

A

A chemical message binds to a protein on the cell surface

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31
Q

What happens in the second stage of intracellular communication- “transduction?”

A

The binding of the signal molecule alters the receptor. This starts a cascade of reactions

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32
Q

What happens in the third stage of intracellular communication- “response?”

A

The transduction pathway triggers a response (ie turning on a gene, activating an enzyme, rearranging the cytoskeleton, etc)

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33
Q

_________ activation leads to __________ signalling cascades and __________ messenger systems

A

Receptor, intracellular, second

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34
Q

Changes in cell function result from:

A

Receptor activation, intracellular signalling cascades, and second messenger systems

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35
Q

What are some examples of “activators” which change the conformation of target proteins?

A

Calcium and cAMP

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36
Q

Signalling molecules can regulate whether a G-protein has bound…

A

GDP or GTP

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37
Q

Phosphorylation is an example of ______________ modification

A

post-translational

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38
Q

G alpha s protein is associated with which enzyme?

A

Adenylate cyclase (activates)

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39
Q

G alpha i protein is associated with which enzyme?

A

Adenylate cyclase (inhibits)

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40
Q

Adenylate cyclase is associated with which second messenger system?

A

cAMP

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41
Q

G alpha q protein is associated with which enzyme?

A

Phospholipase C

42
Q

PLC is associated with which second messenger systems?

A

IP3 and DAG

43
Q

What is the effect of increasing/activating cAMP?

A

Results in an increase in phosphorylation

44
Q

What is the effect of activating IP3/DAG?

A

Activating kinases

45
Q

What is an example of a receptor activated by cAMP?

A

adrenaline receptors in lungs

46
Q

What is an example of a receptor activated by IP3/DAG?

A

Muscarine ACh receptors

47
Q

What is the enzyme that phosphorylates proteins?

A

Kinase

48
Q

What is the enzyme that de-phosphorylates proteins?

A

Phosphatase

49
Q

Serine/threonine kinases are _________ dependent

A

Calcium

50
Q

What are cyclic nucleotides?

A

Second messengers, such as cAMP and cGMP

51
Q

What ions can be transported through a ligand-gated ion channel?

A

Na+, K+, Ca2+, Cl-

52
Q

Ions are transported along what type of gradient in a ligand-gated ion channel?

A

Electro-chemical

53
Q

Ligand-gated ion channels open in response to changes in what?

A

The transmembrane potential

54
Q

How are voltage-gated channels classified?

A

According to the ion that passes through them

55
Q

Which type of receptor is comprised of a single, long polypeptide chain folded 7x with portions inside and outside of the cell?

A

GPCR

56
Q

G protein coupled receptors are also known as

A

Metabotropic receptors

57
Q

G alpha, G beta, and G gamma proteins are associated with which type of transmembrane receptor?

A

GPCR

58
Q

What effect does the G alpha i protein have on phosphorylation?

A

Inhibits

59
Q

What is the effect of stimulating the second messenger system cAMP?

A

activates proteins

60
Q

IP3 and DAG activate __________

A

kinases

61
Q

Acetylcholinesterase inhibitors are examples of drugs that work on what type of receptor?

A

Enzyme linked

62
Q

Signals that are able to cross the cell membrane use what type of receptor?

A

Intra cellular (cytoplasmic/nuclear)

63
Q

What are some examples of substances that use cytoplasmic or nuclear receptors?

A

Steroid hormones, thyroid, retinoic acid

64
Q

Name some important second messengers in the nervous system (5)

A

cAMP, cGMP, DAG, IP3, and calcium ions

65
Q

The difference in electrical potential energy per unit charge between two points.

A

Voltage (V)

66
Q

In physiology, most voltages occur across a __________.

A

membrane

67
Q

The flow of electric charge through a medium (through a surface)

A

Current (I)

68
Q

The opposition to the passage of an electric current

A

Resistance (R)

69
Q

The ability to conduct electric current; the measure of how easily electricity flows along a certain path

A

Conductance (the inverse of resistance)

70
Q

How is Ohm’s law represented?

A

V = I (current) x R (resistance)

71
Q

A property of cellular membranes that only allows certain molecules to enter or exit the cell.

A

Selective permeability

72
Q

Differences in the concentration of ions in the opposite sides of a cell membrane lead to a

A

Voltage, or membrane potential (Vm)

73
Q

This is a measurement of the overall electrical potential energy across the membrane

A

Membrane potential

74
Q

The membrane potential (Vm) depends on the relative _______ current and ____________ of different ions.

A

electrical, conductance

75
Q

Membrane voltage is described in terms of what happens to the ______________ face of the membrane.

A

Intracellular

76
Q

When the inside of the cell membrane is POSITIVE (in relation to the extracellular facing part of the membrane), we say the membrane potential is

A

Positive

77
Q

Cells have a resting membrane potential of

A

-70 to -90 mv

78
Q

What creates current?

A

A flow of ions through a channel

79
Q

The voltage across a membrane depends on which ions are currently…

A

permeable

80
Q

Which ion is typically higher OUTSIDE of the cell?

A

Sodium (Na+)

81
Q

What happens to the voltage of a cell membrane when Na+ channels open?

A

Passive influx of Na+ ions flow IN, making the voltage relatively more POSITIVE. (Think of depolarisation in an action potential)

82
Q

What happens to the voltage of a cell membrane when K+ channels open (after action potential)?

A

Passive flow of K+ ions OUT of the cell, leading to the voltage becoming relatively NEGATIVE again (think of repolarisation).

83
Q

Each ion has a “favourite voltage,” otherwise known as an

A

Equalibrium potential

84
Q

What is the equilibrium potential for sodium ions?

A

+60 mv

85
Q

What is the equilibrium potential for potassium ions?

A

-90 mv

86
Q

What is the equilibrium potential for calcium ions?

A

+123 mv

87
Q

What is the equilibrium potential for chloride ions?

A

-40 mv (or -65 in neurons)

88
Q

If two ion channels were open and the cell was exactly equally permeable to both ions, the membrane potential (Vm) would go to the ___________ between the two equilibrium potentials.

A

average

89
Q

Rapid changes in the Vm that spread rapidly along the nerve fibre membrane. It begins with change from normal resting negative Vm to a positive potential and ends with an almost equally rapid change back to negative potential.

A

Action potential

90
Q

Movement of which ion is responsible for the depolarisation stage of the action potential?

A

Primarily sodium (though calcium channels also open)

91
Q

The period of hyperpolarisation after K+ ions leave the cell is also known as the _________ period

A

refractory

92
Q

What types of stimuli could cause a cell membrane to depolarise?

A

Electrical stimulus (such as a nearby cell depolarising) or a chemical stimulus (synaptic transmission where a NT opens a ligand-gated channel).

93
Q

When Na+ moves into the cell, causing the membrane potential to move closer to 0, which leads to further depolarisation of the membrane, this is known as a

A

positive feedback loop.

94
Q

At which voltage threshold is the cell committed to an action potential?

A

-65 mv to -50 mv

95
Q

The majority of synapses are of what type- electrical or chemical?

A

Chemical

96
Q

During an action potential, the increase in cytosolic free ________ triggers the release of chemical messengers (such as neurotransmitters).

A

calcium

97
Q

Are chemical synapses unidirectional or bidirectional?

A

always unidirectional

98
Q

In electrical synapses, the cells are in direct contact with each other and send ionic signals through a

A

gap junction

99
Q

Action on a post-synaptic cell: input can either be ______ or ________.

A

excitatory or inhibitory

100
Q

If sodium ion channels are open, this will lead to ____________ in the post-synaptic cell.

A

depolarisation

101
Q

What are three ways that signals are terminated within the synaptic cleft?

A
  1. REMOVAL of neutransmitter from synaptic cleft
  2. DEGREDATION by enzymes
  3. RECYCLED into the pre-synaptic cells - (REUPTAKE)

KMMS (58 decks)

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